Screw propeller of helicopter flying machines



R. P. PESCARA SCREW PROPELLER OF HELICOPTER FLYING MACHINES Man 2%, W23831,,449fl129 Filed July 17, 1920 2 sheets-sheet 1 Man 21, 11923.11,449,129

R. P. PESCARA I SCREW PROPELLER OF HELICOPTER FLYING MACHINES I FiledJuly 17, 1920 2-sheetssheen 2 2@ may be considered to be constitutedbythe real-tee aa. a, Teas.

naiTao sTaTas PATENT orator...

ing Machines (for .lem of the steering, propulsion and nane RAUL rni'r ra U S PJESGA, OJ! IBGELONA, SPAIN.

SCREW JPROPELLER 01E HELICOPTER FLYING MACHINES.

1 Application filed July 17, 19%. Serial No. 397,109.

To all whom it may concern! Be it known that l, RAUL PA'rnnAs Pas- CARA,a citizen of the Argentine Republic,

residing at Barcelona," Spain, Calle de la vBuena Suerte No. 20, havemade certain new provision of a system of twoscrew propellers revolvingin opposite directions and, capable of be ng inclined in any directionrelatively to the vertical.

Notwithstanding that theoretical solution of the problem,'it isnevertheless not easy 'to provide a practical solution of the saidproblem owing to all the complications entailed by the execution of theinclining o the apparatus.

Moreover, if it be taken into consideration that in the case of anaccidental stoppage of the engine or engines of an helicopter flyingmachine, the descent under the action of gravity would becomeincreasingly acp celerated. in" such a manner as to become verydangerous, difficulties are encountered which are not calculated toencourage study and investigation relating to machines of that type.

The parachute screw propellers for flying gr type capable of stabilizedby that form the machines. of the helicopter being steered, propelledand inclination in any direction,

subject matter of the present invention, are p designed by their actionalone, to provide a practical solution of the four problem;

p1oying: difi'erential periodical warping,

differential periodically variable incidence, the simultaneousdiminution of incidence of their blades.

By the expression warping screw propellers are to be understood screwpropellers provided with a mechanical device that allows of warpingtheirblades, that is to say, of partially changing their angle of attack insuch amannerthat this variation shall afiect only a more or lessextensive portion of the surfaces by which it is constituted. Thewarping will be differential if, to an increase. of incidence in ablade, there corresponds at the same moment a diminution in the oppositeblade. -Further the said variation will be designated hereinafter asbeing difierential and periodic, when the differential variation of theangle of attack is reproduced periodically at each revolution of theblades.

The same definitions are to apply to the difi'erential periodicallyvar'able variation of incidence with the only di erence that the abovementioned variations of the angle of attack affect the whole of thesurfaces that constitute the blades.

Finally, the expression screw propellers I with simultaneous diminutionof incidence is intended hereinafter to designate screw propellersconstructed in such a manner that the incidence of their blades can bedimin- 'ished or increased during flight, the diminution or increaseeffected at a given instant being equal for all the blades of the screwf propeller under consideration.

It is hereinafter explained how the use of these devices allows ofsolving the hereinb'eforestated problems.

First hewever I will proceed to point out the analogyiexisting betweenthe variable eriodical warping and the periodically var able variationin the incidence. From their definitions it is seen that the warpingwhlch affects only a generally small portion of the surfacesconstituting the blades, allows of obtaining efforts that are much moreaduated in intensity than the variation in the incidence. I shallconsider it therefore as being an improvement on the variable incidenceand, finally, ll shall discuss the ossi'bility' of employing them in oneof the three following ways Y .1. Variable incidence alone,

2. War ing alone,

3. Combination of warping and. dlfi'erential variable incidence.

But since the reasoning that can be em ployed, is the same for thewarping and the 'varlation in the incidence, only t e warping will bedealt with hereinafter for the sake of simplicity. From now yonwards,all

thait1 is stated herein is-intended to applyto bot i e Fig. 4 is a planof a screw propeller of this kind.

On applying the differential periodical warping in such a maiinerthatthe minimum angle of attack shall be situated at A and the maximum-angleof attack shall be situated at B, it will be perceived immediately ishereinafter designated as a direct rotary downward glide (vol plane).Under this designation'is to be understood the descending movement of ahelicopter fiyingmachine retarded by the thrust due to the direct idlerotation of the blades of its screw propellers.

In order that this idle rotation shall be eifective, it is necessarythat it shall take place in accordance with a law corresponds 2 to anangle of attack such that the ratio between "the resistance and thethrust shall be the minimum or in the nei hborhood of the minimum thatcan be obtained with the profile adopted for the blades. In order that 4this law shall operate the blades must retain their normal speed ofrotation by instantaneousdiminution of their angle of attack before thevelocity of the fall becomes too accelerated.

This diminution of the incidence in all the blades corresponds to thedefinition hereinbet'ore given'of the simultaneous diminu tion ofincidence. The later thus certainly allows of executing a direct rotarydownward glide.

I hall now proceed to describe a mechanical arrangement by means ofwhich it is possible to control the warping and the diminution ofincidence.

For the sake of greater clearness I shall divide this description intothree parts v 1. The devices which produce warping effects by theirdirect action upon the air. To such devices I will give the generic nameof warping devices.

2. The mechanism for controlling the warping devices.

The constructional arrangement of a screw propeller blade, for allowingthe simultaneous diminution of incidence and the control of the latter.

1. Warping devices: I

It must be remembered that by this designation I denote any devicewhich, by its direct action upon the air, allows of varying the angle ofattack or of varying the thrust of a restricted portion of tlic blade ofa screw propeller.

Since this arrangement may be carried into execution in severalequivalent ways. I will mention by way of example the following methodof execution An aileron (auxiliary plane) capable of horizontaldeviation in each or only in some of the blades, said aileron beingformed by cutting the actual blade.

It being impossible to give a description of every imaginable system, Ishall take as a type, that of an aileron capable of horizontaldeviation, formed by cutting the actual blade, and capable of movementaround an axle marked 35 in Fig. 2 of the accompanyin drawings.

2. M echanisms for controlling the warp ing devices.

Fig. 1 is a vertical section, and Fig. 2 is a plan of the generalarrangement of the screw propellers.

Figure 3 is a plan view partly in section of a portion of the apparatus.

Figure 4 is a plan view of one of the propellers.

Fig. 5 is a partial plan indicating the working of the control levers.

The central tube 4 serves as an axle for the bosses 5 and 6 of the screwpropellers by means of ball bearings such as 7 and 8. In front of eachblade these bosses 5 and 6 are provided with arms carrying varioussupports 8,9, 10, 11, 12,13, 14, 15. 1 are the bevel toothed wheels bywhich the two screw propellers are coupled together.

The pilot controls the warping by means of the'stick 17 that is movablein all directions around a ball and socket joint 18 fixed to the centraltube 4.

The parts marked 19 and 20 are ball oints fixed to the stick 17, whoseouter rings support arms 21 and 22 that extend through the central tubeand are fixed in the inner ring of the large ball bearing 23, 24 outsidethe central tube. I

The outer ring of this bearing 23 has, in front of each blade, the formof a fork whose prongs terminate in two cylinders such as 25;and 26 inFig. 3 which is a plan of the apparatus on a large scale.

In these cylinders there is adapted to slide a rod 27 which .is rigidlyconnected to a part 28 inside the fixed longitudinal 29 of the blades,and in which it is only capable of sliding by means of straight grooveswhich guide it.

A cable 30 is attached at one end to the part28, and is connected at itsother end to two worm gear segments 31 and 32 which, by their motion.cause the aileron 34 to turn around its axle 35. From Fig. 3 it will beeasy to understand the manner of operation of this arrangement. When thepilot moves maniac constant tendency to maintain the pull in ous ribsthat maintain the adopted profile;

these cables, one of the ailerons will have to turn in a certaindirection whereas the aileron of the opposite blade will have to turn inthe reverse direction. In this manner the diflerential warping isefi'ected.

The same apparatus acts similarly in the other screw propeller so as toproduce an identically, simliar efi'ect.

3. Constructional arrangement of the blade and control of thesimultaneous diminution of the incidence.

The blade is constructed (Figs. 1 and 2) like the wing-ofan aeroplane.36 are vari- 37 and 38 are two wooden longitudinals that couplethemtogether. v

The ribs comprise in the longitudinal axis of the blade, a hole fittedwith a ring of bronge which'allows of the 'passage'of a tubular steellongitudinal 29 rotatably carried in the supports 8 and 9, x

' The blade is consequently movable as a whole on said axle 29. Itterminates in a tube 39 formed on its outside with a very slow pitchedscrewthread 40.

The control of the movement fOr reducing the incidence, which after allreduces itself, to a rotary movement of the blade around the axle 29, isefiected by means or the lever 41. The saidlever 41 comprises a circulardisc-like portion 4:2 which is rotatably mountedwithin the central tubea as d1agrammatically indicated in Figs. 1 and 5. On said disc-likeportion'42 there is secured a circular stud 43 which engages in asuitable horizontal slot in the guide 48.

Guides a7 and 49 are connectedby rods'r l5, 4:6 with the guide 48 sothat all the guides move up and down together within the centube 4:,while said guides are also prov the iiiiit idrthe screwthread 40.

vided with means to prevent their rotation within the tube 4. r l r Theguide l? has lugs that extend through the central tube by way of slots.These lugs support a ball bearing 50 the outer ring '1 of which carriesopposite each blade a link 51jointed' at one end inthe said ring, and at1ts;,ether end in a part 52 that constitutes It will he 'readilyunderstood the nut 52 to move for instance towards the axis of thescrewpropeller. Consequently, since this part 52 is unable to execute anyrotarv motion by reason of the link 51 which holds it fast, the bladewill be compelled to turn around its axis constituted by thelongitudinal 29. In this manner the inshafts.

that ma crating the lever ll, these links will compel machines of thehelicopter type including a number of blades, means for angularlydisplacing said blades about their longitudinal axes, and means forperiodically distorting said blades as the propeller rotates so as toproduce substantially a periodically varying warping efi'ect.

2. A propeller of the kind defined by claim 1 in which the means fordistorting the blades includes ailerons, and means for operating saidailerons. v

3. A propeller of the kind defined by claim 1 in which the means forturning the blades about their longitudial axes includes rotatable.shafts extending through the blades, and meansfor turning said shafts.

4. In combination, an axle, a propeller hub rotatably mounted on saidaxle,'a series of radial shafts carried by said hub, a propeller bladecarried by each of said shafts, screw threads provided upon each of saidshafts, non-rotatable nuts engaging said screw threads, an antifrictionbearing mounted on said axle, links connecting said bearing to'saidnuts, and means for shifting said bearinglongitudinally of said axle tocause shifting of said nuts and rotation of said 5. A combination of theclaim 4: in which the means for shifting said bearing includes anaxially movable sleeve, and means for actuating said sleeve.

6. In combination, a hollowaxle, an antiihriction bearing mounted withinsaid axle and having arms extending through the axle, a second'antifriction bearing arranged exteriorly of the axle and connected tosald armsgmeans for shifting the first mentioned antifriction bearingtoward and away from the am's of said axle, tubular supporting memberscarried by said axle, hladesmounted upon said supporting members, anaileron mounted upon each blade, and controlling means tor the aileronsconnected to sm ailerons, extending through said tubular supporting'members and attached to the second antitriction bearing.

able hubs mounted upon said axle, means for causing the rotation of onehub to impart reverse rotation to the other hub, hollow shafts rotatablymounted in said hubs, means for rotating said shafts, a blade mounted oneach shaft, an aileron mounted on each blade, an antifriction bearingfor kind defined by i not llll

its

7. In combination, a hollow axle, rotat- &

- one of said bearings away from the axis of the axle in one directionand to simultaneously move the other bear ng away from the axis of theaxle in a diametrically op- I posite direction, and connecting means at-10 tached to said bearings, extending through marinas said shafts andconnected to said ailerons for controlling th'emovement of said aileronsby said stick.

In testimony whereof I have signed my name to this specification.

RAUL PATERAS PESCARA.

Witnesses: v 1

ENSEBIO GARCIA,

l JosE bALAz.

